Drawing referenced into a Sheet is masking another Drawing

I am using ABD SS6 V8i, we have design models, composition models, drawings and sheets.  Drawings were created from saved view in composition file.  We have a problem where a drawing referenced on a sheet is masking another drawing ( overall plan drawing and Stair drawing).  I have tried update sequence but it doesn't do anything.  If I turn off reference display and only show individually I can see that it's is there, that's how I know its been masked by the other Drawing reference.

Any ideas on how to solve this?